Fantasy: Machu Picchu, Peru
Machu Picchu was an ancient Andean community built high in the mountains. It was built by the Inca in the 15th century and the citadel in the clouds made them virtually uninvadable.
Incredibly, Machu Pichu was not known to the larger global community until an American historian publicized it in 1911. This is due in part to the Inca abandoning the settlement around 1450 during the Spanish conquest.